https://www.oslobors.no/ob_eng/Oslo-Boers/Trading/Market-surveillance/Market-interference
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There are a variety of reasons that make it necessary to use a matching halt. A matching halt may, for example, be appropriate if a price sensitive announcement is about to be released. A matching halt will then give market participants time to evaluate the new information and decide whether they wish to cancel any of the orders they have entered in the trading system.A matching halt may also be appropriate if there is a suspicion that some market participants have information that is not known by other participants, or if the security in question shows unusual changes in price or traded volume. In this kind of situation, a matching halt is used to provide Oslo Børs time to investigate whether some participants in the market have access to information about the company in question that is not available to all participants, or if there are other circumstances that are causing an unusual trading pattern.
A matching halt normally lasts for a short period of time. […]